Hemostasis valves are well known and used in a variety of percutaneous medical procedures that require the insertion of a catheter or other instruments and devices into a patient's body. For example, hemostasis valves enable the introduction and operation of catheters and other instruments into a patient's cardiovascular system during a minimally invasive interventional procedure. Typically, a guide catheter or introducer is connected to a distal end of the hemostasis valve, and an operating instrument is inserted into a proximal end and through the guide catheter or introducer to a desired location in the patient. Once the instrument is in place, the valve is closed around the instrument, thereby establishing a seal to prevent blood from escaping from the body of the patient.
Existing hemostasis valves, however, generally do not allow variable control over the strength of the seal within the hemostasis valve. Rather, most hemostasis valves use flaps or other zero-closure valves that simply move into different positions as the instrument is inserted through the valve. These flaps often fail to form a fluid-tight seal around the full structure of the inserted instrument, thereby allowing fluids to escape past the valve. Additionally, many hemostasis valves do not fully adapt to large or irregularly sized instruments. This results in unintended leakage and bleeding despite the use of the hemostasis valve during medical procedures.